Conversion of hydrocarbons

ABSTRACT

Isoparaffins are converted in a reaction zone to other hydrocarbons including isoparaffins containing fewer carbon atoms per molecule and isoparaffins containing more carbon atoms per molecule by contacting an isoparaffin feedstock with hydrofluoric acid in the presence of an amount of an olefin which is sufficient to increase the conversion of said feedstock. In a combination process said isoparaffin product containing fewer carbon atoms per molecule than the isoparaffin feedstock is passed to an alkylation zone as a portion of one of the reactants thereto. Isoparaffin product containing the same number of carbon atoms as said first-mentioned isoparaffin feedstock, and which are produced in said alkylation zone, are passed to the firstmentioned reaction zone as a portion of the feedstock thereto. Isoparaffin product containing more carbon atoms per molecule are blended with at least a portion of the hydrocarbon product produced in the alkylation zone.

United States Patent Hutson, Jr. et al. 1 July 25, 1972 54] CONVERSION OF HYDROCARBONS 57 ABSTRACT [72] Inventors: Thomas Hutson, Jr.; Cecil 0. Carter, both of Barllesville, Oklalsoparaffins are converted in a reaction zone to other [73] Assigneez Phillips Petroleum Company hydrocarbons including isoparaffins containing fewer carbon atoms per molecule and isoparaffins containing more carbon Filed: y 1970 atoms per molecule by contacting an isoparaffin feedstock [211 App. No; 36,528 with hydrofluoric acid in the presence of anamount of an olefin whlch IS sufficient to increase the conversion of said 1 feedstock. in a combination process said isoparaffin product 52 U.S. Cl. ..260 676 R, 260/683.48 containing fewer carbon moms per molecuk than the [51] Int. Cl. ..C07c 3/54, C07c 3/62, C07c 9/l6 iSopm-affln f d t k is passed to an alkyhtion zone as a [58] Field of Search... ..260/683.48, 676 R [ion of one of the reactants thereto lsopamffin'pmduct com taining the same number of carbon atoms as said first-men- [56] References Clted tioned isoparaffin feedstock, and which are produced in said UNITED STATES PATENTS alkylation zone, are passed to the first-mentioned reaction zone as a portion of the feedstock thereto. lsoparafi'm product 2,662,103 12/1953 Matus zak ..260/683.48 containing more carbon atoms per molecule are blended with $691,638 1954 Schnelder -260/676 R at least a portion of the hydrocarbon product produced in the 2,375,867 5 1945 Newman ..260/683.45 alkylation zone,

Primary Examiner-Delbert E. Gantz Assistant Examiner-G. J. Crasanakis Attorney-Young and Quigg 24 RERUN UN IT l 15 Claims, 1 Drawing Figure PR AN /OPE Ln-BUTANE RERUN HF DISTILLATION DISTILLATION HEAVY ALKYLATE CONVERSION OF HYDROCARBONS This invention relates to the conversion of hydrocarbons.

For quite a number of years motor fuels have contained appreciable quantities of low boiling hydrocarbons for the purpose of imparting desired vapor pressure and distillation characteristics to the motor fuel. One class of hydrocarbons which has been used in this manner is the low boiling isoparaffin hydrocarbons, e.g., isopentane. Such hydrocarbons not only have the desired vapor pressure and volatility characteristics, but they also possess desired antiknock properties. However, the use of said low boiling isoparafiin hydrocarbons has disadvantages in that due to their volatility they vaporize readily from the motor fuel while it is in storage and while in the fuel tank of the vehicle. This vaporization not only represents a loss of fuel, but also contributes to pollution of the atmosphere. It would be desirable to eliminate said low boiling isoparafr'ins as a component of motor fuels. However, merely eliminating said isoparaffin hydrocarbons would involve considerable economic loss due to the loss of volume of the hydrocarbons involved. It would be more desirable to convert said isoparaffins to other more valuable hydrocarbons and thus maintain the volume of motor fuel while at the same time improving the quality of the motor fuel and eliminating "the problems of atmospheric pollution. It is known that paraffins can be subjected to the action of concentrated hydrofluoric acid and converted by a reconstruction or disproportionation reaction into other hydrocarbons containing fewer carbon atoms per molecule and containing more carbon atoms per molecule. For example, see US. Pats. No. 2,403,649; 2,403,650; and 2,418,023, all assigned to Phillips Petroleum Company. However, said reaction is normally carried out at elevated temperatures and/or employing extended contact or residence times in the reaction zone.

The present invention provides a solution to the above problems. We have now discovered that the presence of olefins in the reaction zone markedly increases the efficiency of said reconstruction or disproportionation reaction by increasing the conversion of the isoparaffin feedstock and making it possible to carry out said reaction at lower temperatures and/or with shorter residence or contact times. We have discovered that isoparaffin feedstocks can be converted to other hydrocarbons including an isoparaffin product containing fewer carbon atoms per molecule and an isoparafiin product containing more carbon atoms per molecule than said feedstock by contacting said feedstock with a concentrated hydrofluoric acid in the presence of an amount of an olefin which is sufficient to increase the amount of conversion of said feedstock and/or decrease the contact or residence time. In a preferred combination process of the invention, said isoparaffin product produced in a first reaction zone, and containing fewer carbon atoms per molecule than the isoparaffin feedstock, is passed to an alkylation zone as one of the reactants used therein; isoparaffin product produced in said alkylation zone and containing the same number of carbon atoms as the isoparaffin feedstock to the first reaction zone are passed from the alkylation zone to said first reaction zone; and isoparaffin product produced in said first reaction zone, and containing more carbon atoms per molecule than the isoparaffin feedstock thereto, are blended with at least a portion of the hydrocarbon product produced in the alkylation zone.

An object of this invention is to provide a method for reconstructing or disproportionating isoparaffin feedstocks into other hydrocarbons including an isoparaffin containing fewer carbon atoms per molecule and an isoparaffin containing more carbon atoms per molecule than the feedstock. Another object of this invention is to provide a method for converting volatile isoparaffin components normally used in motor fuels into less volatile and more valuable motor fuel components. Another object of this invention is to provide a combination process wherein an isoparaffin feedstock is converted in a first reaction zone into other hydrocarbons including an isoparaffin product containing fewer carbon atoms per molecule and an isoparaffin product containing more carbon atoms per molecule than the feedstock to said first reaction zone, said isoparaffin product containing fewer carbon atoms per molecule is then alkylated with an olefin to produce valuable alkylate motor fuel components, and isoparaffin products which are produced in said alkylation zone and which are like said feedstock to the first reaction zone are separated from the alkylate and returned to said first reaction zone. Other aspects, objects, and advantages of the invention will be apparent to those skilled in the art in view of this disclosure.

Thus, in a preferred embodiment of the invention, there is provided a process for converting an isoparaffin feedstock containing at least five carbon atoms per molecule into other hydrocarbons including an isoparaffin product containing fewer carbon atoms per molecule than said feedstock and an isoparaffin product containing more carbon atoms per molecule than said feedstock, which process comprises: contacting said feedstock in a reaction zone with concentrated hydrofluoric acid under reaction conditions of temperature, pressure, and time sufficient to effect said conversion, and in the presence of an olefin containing at least three carbon atoms per molecule and which is present in an amount sufficient to increase said conversion of said feedstock.

Further according to the invention, there is provided a process for the production of hydrocarbons useful in motor fuel, which process comprises, in combination, the steps of: contacting an isoparaffin feedstock containing from five to seven carbon atoms per molecule with concentrated hydrofluoric acid in a reaction zone under reaction conditions of time, temperature, and pressure sufficient to convert at least a portion thereof into other hydrocarbons including an isoparaffin product containing fewer carbon atoms per molecule than said feedstock and an isoparaffin product containing more carbon atoms per molecule than said feedstock; recovering said isoparaffin product containing fewer carbon atoms than said feedstock from a hydrocarbon effluent stream from said reaction zone and passing same to an alkylation zone; in said alkylation zone, alkylating said recovered isoparaffin product with an olefin containing from three to five carbon atoms per molecule to produce products including alkylate and another isoparaffin product containing the same number of carbon atoms as said isoparaffin feedstock; recovering said another isoparaffin product from a hydrocarbon effluent stream from said alkylation zone; and passing said recovered another isoparaffin product to said reaction zone as a portion of said isoparaffin feedstock thereto.

isoparaffin hydrocarbons which can be used as feedstock to the reconstruction or disproportionation step of the invention include those having at least five carbon atoms per molecule. Whenoperating to produce components for motor fuels, the more preferred isoparaffin feedstocks are those containing from five to seven carbon atoms per molecule. The isopentanes, e.g., Z-methylbutane, are presently the most preferred feedstock for making motor fuel components. Said isoparaffin feedstocks can be obtained from any convenient source. Presently preferred sources are streams resulting from petroleum refining operations and streams recovered from processing of natural gases to recover normally liquid hydrocarbons therefrom. Such streams will frequently contain other saturated hydrocarbons. It is preferred that said streams be comprised predominantly of isoparaffin hydrocarbons, more preferably that they contain at least 60 per cent isoparaffins by volume.

Olefins which can be used in the practice of the invention include the monoolefins containing at least three carbon atoms per molecule. Presently preferred olefins for use in the practice of the invention are those monoolefins containing from three to five carbon atoms per molecule, e.g., propenes, butenes, and pentenes. Said olefins are preferably used in amounts which are sufficient to increase the conversion of the isoparaffin feedstock, preferably to at least 10 weight per cent. Generally speaking, from about 1 to about l0, preferably from about 1 to about 5, weight per cent of olefin, based on the isoparaffin feedstock, can be used in the practice of the invention. Higher quantities can sometimes be used. However, at olefin quantities above about weight per cent, selectivity to the disproportionation or reconstruction reaction decreases and some alkylation is obtained.

Operating conditions employed in the reconstruction or disproportionation step of the invention are interrelated and a change in one of the conditions will frequently affect the other conditions as will be understood by those skilled in the art in view of this disclosure. Generally speaking, and as a guide to those skilled in the art, the preferred temperature will generally be in the range of about 60 to about 150 F. The pressures employed are, generally speaking, not critical. It is preferred to employ sufficient pressure so as to maintain the hydrocarbon reactants and the hydrofluoric acid catalyst in liquid phase. When operating at the above preferred temperatures, pressures in the range of 125 to 250 psig can be conveniently employed. Higher pressures would be employed at higher temperatures. The isoparaffin to hydrofluoric acid weight ratio can conveniently be in the range of about 0.06 to 5.0, preferably 0.3 to 3. The residence time in the reactor will preferably be within the range of about to about 150 seconds, although longer residence times can be employed.

The use of said olefins in the reaction zone of the reconstruction or disproportionation step of the invention makes it possible to carry out the reaction at much lower temperatures, e.g., substantially atmospheric temperatures, and to use much shorter residence times. Thus, when said olefins are not present in the reaction zone, the temperature therein will usually be in the order of 175 to 250 F. (while maintaining liquid phase), and the residence time will usually be in the order of 200 to 1,000 seconds, or more, for about the same feedstock conversion.

The alkylation step, per se, employed in the combination process of the invention is conventional and well known in the art. Most commonly, an isoparaffin such as isobutane is alkylated with a monoolefin containing from three to five carbon atoms per molecule, e.g., propylene, butylenes, isobutylenes and isoarnyle'nes. lsobutane and isobutylene are the presently preferred reactants for use as reactants in said alkylation step.

The operating conditions employed in the alkylation step of the invention can be any of the conditions well known in the art. For example, the alkylation reaction can be carried out at a temperature preferably within the range of about 60 to about 150 F a pressure preferably within the range of about 125 to about 250 psig, and preferably using a hydrocarbon to hydrofluoric acid weight ratio within the range of about 0.05 to about 5.0, more preferably within the range of 0.3 to 3. The total isoparaffin to olefin mol ratio in the alkylation zone will preferably be in the range of about 4 to about 36. The residence time in the alkylation zone will preferably be in the range of 1 to about 250 seconds. I

The hydrofluoric acid catalyst used in the practice of the invention can be the well known hydrofluoric acid used commercially in hydrofluoric acid alkylation processes. Preferably, said acid is essentially anhydrous, although small quantities of water, e.g., from about 0.1 weight per cent to about 5 weight per cent, can be present. Preferably, said hydrofluoric acid catalyst will contain at least about 86 weight per cent HF. A convenient and practical range for the HF content is from about 86 to about 96 weight per cent HF.

The drawing is a diagrammatic flow sheet illustrating the several embodiments of the invention.

Referring now to the drawing, the invention will be more fully explained. It will be understood that many valves, pumps, control instruments, etc., not necessary for explanation of the invention, have been omitted for the sake of brevity. For convenience, and not by way of limitation, the invention will be further described with particular reference to using an isopentane, e.g., 2-methylbutane, as feedstock in the reconstruction or disproportionation step of the invention. Similarly, the invention is not to be limited to the particular feedstocks used in the alkylation step of the invention. It is within the scope of the invention to use other feedstocks in both of said steps. It

should also be understood that the representative temperatures and pressures set forth hereinafter in describing the drawing are only illustrative of the temperatures and pressures which can be utilized in the practice of the invention. The par ticular temperatures and pressures utilized in any particular reaction or separation will depend upon the nature and composition of the particular feedstock(s) to the particular reaction or separation step.

Referring now specifically to the drawing, a stream of 2- methylbutane in conduit 10, a stream of propylene-from conduit l2, and a recycle stream comprising 2-methylbutane from conduit 14 are mixed in conduit reactor 16 with a circulating stream of concentrated hydrofluoric acid from conduit 15 containing, for example, about weight per cent HF, and introduced into phase separator 18. Said mixing can be accomplished in any known manner such as by employing a mixing tee, mixing orifices in conduit 16, etc. A portion of said circulating stream of hydrofluoric acid is withdrawn via conduit 20, as necessary, and passed to HF rerun unit 22. Said HF rerun unit is operated in conventional manner with acid-soluble oils and other impurities being removed therefrom via conduit 24. Rerun acid can be withdrawn via conduit 26 and used as make-up acid in separator 18 as necessary. Fresh make-up HF acid can also be introduced via conduit 26 from a source not shown.

Said conduit reactor 16 and separator 18 can be any suitable type of reactor for effecting further contact (if desired), and a subsequent separation, between the hydrocarbon stream charged thereto and the hydrofluoric acid catalyst. For example, see the patents mentioned hereinafter in connection with conduit reactor 50. The temperature in said reactor can be conveniently controlled by means of the cooler on the circulating stream of acid in conduit 15. A phase separation is effected in said separator 18 with a hydrocarbon stream being drawn from said reactor via conduit 28 and introduced into a first fractionation zone, here represented by deisobutanizer column 30. Typical operating conditions on column 30 include a top tower temperature of about 120 F. and a pressure of about psig. A bottoms product stream comprising unreacted isopentane (2-methylbutane) is withdrawn from column 30 via conduit 32 and processed as described further hereinafter. A portion of said bottoms product stream is heated by means of the heater shown and returned to column 30 for supplying heat thereto.

An overhead stream comprising isobutane is withdrawn from column 30 via conduit 34, passed through the condenser and accumulator shown, and a portion thereof returned to said column 30 via conduit 36 as reflux. If desired, the

remainder of said overhead stream comprising isobutane can be recovered as a product of the process. In the combination process of the invention said remainder stream comprising isobutane is passed via conduit 38 and conduit 40 into conduit 42. If desired, fresh make-up isobutane can be introduced into conduit 40 via conduit 44. A stream of olefins comprising propylene and/or butylenes and/or amylenes is introduced into conduit 42 via conduit 46. Recycle isobutane, obtained as described hereinafter, is introduced into conduit 42 via conduit 48. The resulting mixture in conduit 42 is then'contacted in conduit reactor 50 with a stream of circulating concentrated hydrofluoric acid from conduit 49. A portion of the circulating acid in conduit 49 can be withdrawn via conduit 52 and introduced into HF acid rerun unit 22 similarly as described above in connection with conduit 15 and conduit reactor 16. Regenerated HF acid can be returned to conduit reactor 50 by means of conduit 26 as needed. Fresh make-up HF acid can also be introduced via conduit 26, as needed, from a source not shown. The mixture of hydrocarbons and hydrofluoric acid in conduit reactor 50 is introduced into phase separator 54. Said conduit reabtor 50 and separator 54 can be any suitable type of reactor system known in the art. Typical systems are shown in US Pat. No. 3,213,157 and 3,435,092, both assigned to Phillips Petroleum Company. The temperature in the reactor can be conveniently controlled by means of the cooler on the stream of circulating acid in conduit 49. If desired, mixing orifices or other suitable type of mixing means can be installed in said reactor conduit 50, similarly as described above for conduit 16. A phase separation between hydrocarbons and the hydrofluoric acid catalyst is effected in said vessel 54.

A hydrocarbon stream comprising alkylate and unreacted hydrocarbons is withdrawn from phase separator 54 via conduit 56 and introduced into a second fractionation zone, here represented by column 58 which can also be referred to as an isostripper. An overhead stream comprising unreacted isobutane is withdrawn from column 58 via conduit 60, passed through the condenser and accumulator shown, and a portion thereof returned to column 58 via conduit 62 as reflux. The remainder or net yield of said overhead stream comprising unreacted isobutane is passed via conduit 64 with a portion thereof going to said conduit 48 as the recycle isobutane stream returned to reactor 50. The remainder of the stream in said conduit 64 (sufficient to prevent buildup of propane in the alkylation system) is passed via conduit 66 into depropanizer tower 68. The division of the stream in conduit 64 between conduits 48 and 66 can be controlled by suitable flow control valves, not shown. Typical operating conditions in tower 68 include a top temperature of about 120 F., a bottom temperature of about 215 F., and a pressure of about 275 psig.

An overhead stream comprising propane is withdrawn from column 68 via conduit 70, passed through the condenser and accumulator shown, and a portion thereof returned to said column 68 via conduit 72 as reflux. Accumulator 71 is provided with a collection or drawoff sump as shown. Recycle HF acid can be withdrawn via conduit 73 and returned to conduit reactor 50 or passed to conduit reactor 16 as needed or desired. The remainder of the overhead stream from accumulator 71 which is not used as reflux in tower 68 is passed via conduit 74 into stripper tower 76. Overhead from stripper tower 76 comprising HP is returned to accumulator 71 via conduit 78. A bottoms stream comprising propane is withdrawn from stripper column 76 via conduit 80. Heat for said tower 76 is supplied by heating a portion of the stream in conduit 80 by means of the heater shown.

Returning now to fractionator column 58, a bottoms product streaii't'comprising alkylate and isopentane (Z-methylbutane) is withdrawn via conduit 82, a portion thereof returned to column 58 via the heater arrangement shown, and the remainder introduced into a third fractionation zone, here represented by debutanizing column 84. An overhead stream comprising normal butane is withdrawn from column 84 via conduit 86, passed through the condenser and accumulator shown, a portion returned to column 84 as reflux, and the remainder withdrawn via conduit 88. Typical operating conditions in column 84 would include a top tower temperature of about 128 F., a bottom tower temperature of about 290 F., and a pressure of about 60 psig.

Bottoms product from column 84 is withdrawn via conduit 90, with a portion thereof being used for supplying heat to the column, and the remainder introduced into a fourth fractionation zone here represented by deisopentanize'r column 91. An overhead stream comprising isopentane (Z-methylbutane) is withdrawn from column 91 via conduit 92, passed through the condenser and accumulator shown, and a portion returned to column 91 as reflux via conduit 93. Said overhead stream comprising isopentane includes the unreacted isopentane from reconstruction or disproportionation reactor 18 and also the isopentane produced in alkylation conduit reactor 50. The portion of said overhead stream comprising isopentane not used as reflux in tower 91 is passed via conduit 14 as recycle to said first conduit reactor 16.

Bottoms product comprising isoparafi'rns having more carbon atoms per molecule than said isopentane charge, e.g., isohexanes, and higher boiling alkylate is withdrawn from column 91 via conduit 94 If desired, said bottoms product stream in conduit 94 can be passed to column 95, or any other suitable type of fractionation means, for the separation of a light alkylate stream which can be removed via conduit 96 and a heavy alkylate stream which can be removed via conduit 97. If desired, said light alkylate stream in conduit 96 can be further fractionated to separate the isohexanes and light alkylate.

The following examples will serve to further illustrate the invention.

EXAMPLE I A series of runs was carried out for the disproportionation or reconstruction of 2-methylbutane in the presence of varying amounts of propylene and concentrated HF catalyst. A control run in which no propylene was used was also carried out. These runs were carried out in a continuous manner in a reactor system comprising the essential components of reactor 16 in the drawing. A feedstock consisting essentially of 2- methylbutane and propylene (when present) was contacted with concentrated hydrofluoric acid containing about 91 weight per cent HF. The hydrocarbon to acid weight ratio in all runs was about 2.5. The temperature in the reactor in all runs was 100 F. i 5. The reactor pressure in all runs was 195 psig 5 psig. The contact time or residence time in all runs was in the range of 35 to 45 seconds for an average of about 40 seconds. The reactor efiluent from each run was analyzed in conventional manner by fractional distillation. Table I below sets forth feedstock compositions, product analysis, and conversion values for said runs.

TABLEI Run Number 1 2 3 4 5 Feedstock Wt. Propylene O l 2 3 4 Reactor Efiluent Composition, Wt. Propane trace Isobutane 0.8 lsopentanes 98.5 lsohexanes 0.7 Heptanes, plus trace Conversion, Wt. 1.4

EXAMPLE II In this illustrative embodiment two runs are carried out in accordance with the combination process of the invention illustrated in the drawing. In Run 6 an isopentane (Z-methylbutane) feedstock is converted in the reactor system comprising conduit 16 and separator 18 at a temperature of about 100 F., a pressure of about psig, a hydrocarbon to HF acid weight ratio ofO. 14, a contact or residence time of about 40 seconds, and in the presence of about 3.9 weight per cent propylene contained in the feedstock. The reactor effluent in conduit 28 is processed essentially as described above in connection with the drawing, with the stream in conduit 38 comprising isobu tane from tower 30 being passed to the alkylation zone comprising reactor conduit 50 and separator 54. In reactor 50 said isobutane together with recycle isobutane from conduit 48 is used to alkylate a stream of monoolefms comprising propylene and butylenes. Reaction conditions in reactor 50 are: temperature about 70 F., pressure about psig,

hydrocarbon to HF acid weight ratio about 0.13, isobutane to olefin weight ratio about 12.3, and residence or contact time about 25 seconds. The concentrated HF acid used in both reactor 16 and reactor 50 contains about 91 weight per cent HF. Reactor efiluent in conduit 56 is processed essentially as described above in connection with the drawing.

Run No. 7 is carried out under essentially the same conditions except that no propylene is included in the feedstock to reactor 16. The material balance set forth below in Table 11 shows stream compositions and quantities.

TABLE II Run Run Stream No.

Composition No. 6 No. 7 10 Fresh isopentane, BID 2,020 65 12 Propylene, B/D 220 14 Recycle lsopentane, B/D 2,570 4,525 Vol. iC 98 98 32 Tower 30 Bottoms, B/D 3,730 4,575

Vol. nC, and lighter trace trace Vol. iC: 68.1 98.1 Vol. lC 'S 15.0 0.9 Vol. nC and heavier 16.9 1.0 38 Tower 30 Overhead, B/D 927 Vol. HF 0.6 0.6 C 81. lighter 29.3 29.3 iC 69.6 69.6 nC & heavier 0.5 0.5 44 Fresh lsobutane, BID 0 645 46 Olefin Feed, BID 1,160 1,160

Vol.%C;, 21.9 21.9 Vol. C 22.9 22.9 Vol. ic, 24.2 24.2 Vol.%C,-- 31.0 31.0 48 Recycle lsobulane, BID 7,700 7,700 Vol. i6, 95 95 66 Feed to Tower 68, B/D 2,590 2,590 40 Bottoms from Tower 68, B/D 2,270 2,270 80 Propane Yield 288 288 82 Tower 58 Bottoms, B/D 1,055 1,055

Vol. nil 8L lighter 1.02 1.02 Vol. iC, 2.00 2.00 Vol. iQ, 8L heavier 96.98 96.98 88 Normal Butane Yield, B/D 13 13 96 Light Alkylate, BID 2,093 1.036 97 Heavy Alkylate, B/D 107 54 *B/D barrels per day The data in Table I1 illustrate the advantages of the combination process of the invention, particularly when an olefin, e.g., propylene, is used in the reconstruction or disproportionation step of the invention. For example, in Run No. 6 it is possible to charge 2,020 barrels per day of fresh isopentane when including only 220 barrels propylene as compared to only 65 barrels per day in Run No. 7 when not using propylene. It should also be noted that in Run 6 there is produced 2,093 barrels per day of light alkylate as compared with only 1,036 barrels per day in Run 7. Thus, in Run 6 a much greater quantity, 1,955 barrels, of 2-methylbutane has been upgraded to light alkylate. 1n the above illustrative embodiment of the invention, Run No. 7 is shown as being carried out under the same conditions as Run No. 6 for comparative purposes. While it is usually always preferred to use an olefin, e.g., propylene, in the reconstruction or disproportionation step of the combination process of the invention, said combination process is not so limited. Thus, it is within the scope of said combination process to employ higher temperatures, for example, or longer contact times, as set forth above, in the reconstruction or disproportionation step thereof to increase the conversion when no olefin is used in said step. 1

While certain embodiments of the invention have been described for illustrative purposes, the invention is not limited thereto. Various other modifications or embodiments of the invention will be apparent to those skilled in the art in view of this disclosure. Such modifications or embodiments are within the spirit and scope of the disclosure.

We claim:

1. A process for the production of hydrocarbons useful in motor fuel, which process comprises, in combination, the steps of: contacting an isoparaffin feedstock containing from five to seven carbon atoms per molecule with concentrated hydrofluoric acid and an olefin containing from three to five carbon atoms per molecule in a reaction zone under reaction conditions of time, temperature, and pressure sufficient to convert at least a portion thereof into other hydrocarbons including an isoparafiin product containing fewer carbon atoms per molecule than said feedstock and an isoparaffin product containing more carbon atoms per molecule than said feedstock, said olefin being present in an amount sufiicient to increase the conversion of said feedstock into said lsoparaffin product containing fewer carbon atoms per molecule and said isoparaffin product containing more carbon atoms per molecule than said feedstock; recovering said isoparaffin product containing fewer carbon atoms than said feedstock from a hydrocarbon efiluent stream from said reaction zone and passing same to an alkylation zone; in said alkylation zone, alkylating said recovered isoparaffin product with an olefin containing from three to five carbon atoms per molecule to produce products including alkylate and another isoparaffin product containing the same number of carbon atoms as said isoparafiin feedstock; recovering said another isoparaffin product from a hydrocarbon efi'luent stream from said alkylation zone; and passing said recovered another isoparaffin product to said reaction zone as a portion of said isoparaffin feedstock thereto.

2. A process according to'claim 1 wherein: the amount of said olefin present is an amount sufficient to increase said conversion to at least about 10 weight per cent; and at least one of said isoparaffin products is recovered from an effluent stream from said reaction zone.

3. A process according to claim 1 wherein the temperature in said reaction zone is within the range of from about 60 to about F.

4. A process according to claim 1 wherein said olefin is present in said reaction zone in an amount within the range of from about 1 to about 10 weight per cent, based on the isoparaffin in said feedstock.

5. A process according to claim 4 wherein: said temperature is within the range of from about 60 to about lso F.; said pressure is sufficient to maintain said hydrocarbons and said hydrofluoric acid in essentially liquid phase; and said contacting is carried out for a period of time within the range of about 15 to about 150 seconds.

6. A process according to claim 5 wherein: said feedstock comprises 2-methylbutane; said olefin comprises propene; one of said products comprises isobutane; and another of said products comprises an isohexane.

7. A process according to claim 6 wherein the amount of said olefin present in said reaction zone is within the range of from about 1 to about 5 weight per cent.

8. A process according to claim 1 wherein: said hydrocarbon efiluent stream from said reaction zone is fractionated in a first fractionation zone to recover a first stream comprising said product containing fewer carbon atoms per molecule than said feedstock and a second stream comprising ,said product containing more carbon atoms per molecule than said feedstock, and unconverted feedstock; said first stream is passed to said alkylation zone; said hydrocarbon efiluent stream from said alkylation zone is fractionated in a second fractionation zone to recover therefrom a stream comprising a normal paraffin containing fewer carbon atoms than said feedstock isoparatfin, said another isoparaflin product containing the same number of carbon atoms as said isoparlffin feedstock, and alkylate; said last-mentioned stream is fractionated in a third fractionation zone to recover an overhead product stream comprising said normal paraffin and a bottom product stream comprising said another isoparaffin product containing the same number of carbon atoms as said isoparaffin feed: stock; said bottom product stream is passed to a fourth fractionation zone; said second stream is passed to said fourth fractionation zone; and said another isoparaffin is recovered from said fourth fractionation zone and recycled to said firstmentioned reaction zone as a portion of the charge stock thereto.

9. A process according to claim 8 wherein the temperature in said first-mentioned reaction zone is within the range of from about 60 to about 250 F.

10. A process according to claim 8 wherein: the temperature within said first-mentioned reaction zone is within the range of from about 60 to about 150 F.; said pressure is sufficient to maintain said hydrocarbons and said hydrofluoric acid in essentially liquid phase; and said contacting is carried out in the presence of an olefin selected from the group consisting of propene and butenes and mixtures thereof which is sufficient to increase said conversion of said feedstock.

11. A process according to claim 10 wherein said olefin is present in an amount within the range of from about 1 to about 10 weight per cent, based on said feedstock.

12. A process according to claim 11 wherein said olefin is present in an amount within the range of from about 1 to about 5 weight per cent.

13. A process according to claim 11 wherein: said feedstock comprises 2-methylbutane; said olefin comprises propene; one of said products from said first reaction zone comprises isobutane; and another of said products from said first reaction zone comprises an isohexane.

l4. A process according to claim 1 wherein: said alkylation is carried out in the presence of concentrated hydrofluoric acid; used hydrofluoric acid from said alkylation zone and used hydrofluoric acid from said first reaction zone are passed to a common hydrofluoric acid rerun zone; and rerun hydrofluoric acid from said acid rerun zone is returned as needed to said alkylation zone and to said first reaction zone.

15. A process according to claim 1 wherein: said olefin is selected from the group consisting of propene,

butenes, and mixtures thereof; said feedstock comprises 2-methylbutane; said isoparafiin product containing fewer carbon atoms per molecule than said feedstock comprises isobutane; said isoparaffin product containing more carbon atoms per molecule than said feedstock comprises an isohexane; and said another isoparafi'ln product containing the same number of carbon atoms as said feedstock comprises 2- methylbutane. 

2. A process according to claim 1 wherein: the amount of said olefin present is an amount sufficient to increase said conversion to at least about 10 weight per cent; and at least one of said isoparaffin products is recovered from an effluent stream from said reaction zone.
 3. A process according to claim 1 wherein the temperature in said reaction zone is within the range of from about 60* to about 150* F.
 4. A process according to claim 1 wherein said olefin is present in said reaction zone in an amount within the range of from about 1 to about 10 weight per cent, based on the isoparaffin in said feedstock.
 5. A process according to claim 4 wherein: said temperature is within the range of from about 60* to about iso* F.; said pressure is sufficient to maintain said hydrocarbons and said hydrofluoric acid in essentially liquid phase; and said contacting is carried out for a period of time within the range of about 15 to about 150 seconds.
 6. A process according to claim 5 wherein: said feedstock comprises 2-methylbutane; said olefin comprises propene; one of said products comprises isobutane; and another of said products comprises an isohexane.
 7. A process according to claim 6 wherein the amount of said olefin present in said reaction zone is within the range of from about 1 to about 5 weight per cent.
 8. A process according to claim 1 wherein: said hydrocarbon effluent stream from said reaction zone is fractionated in a first fractionation zone to recover a first stream comprising said product containing fewer carbon atoms per molecule than said feedstock and a second stream comprising said product containing more carbon atoms per molecule than said feedstock, and unconverted feedstock; said first stream is passed to said alkylation zone; said hydrocarbon effluent stream from said alkylation zone is fractionated in a second fractionation zone to recover therefrom a stream comprising a normal paraffin containing fewer carbon atoms than said feedStock isoparaffin, said another isoparaffin product containing the same number of carbon atoms as said isoparaffin feedstock, and alkylate; said last-mentioned stream is fractionated in a third fractionation zone to recover an overhead product stream comprising said normal paraffin and a bottom product stream comprising said another isoparaffin product containing the same number of carbon atoms as said isoparaffin feedstock; said bottom product stream is passed to a fourth fractionation zone; said second stream is passed to said fourth fractionation zone; and said another isoparaffin is recovered from said fourth fractionation zone and recycled to said first-mentioned reaction zone as a portion of the charge stock thereto.
 9. A process according to claim 8 wherein the temperature in said first-mentioned reaction zone is within the range of from about 60* to about 250* F.
 10. A process according to claim 8 wherein: the temperature within said first-mentioned reaction zone is within the range of from about 60* to about 150* F.; said pressure is sufficient to maintain said hydrocarbons and said hydrofluoric acid in essentially liquid phase; and said contacting is carried out in the presence of an olefin selected from the group consisting of propene and butenes and mixtures thereof which is sufficient to increase said conversion of said feedstock.
 11. A process according to claim 10 wherein said olefin is present in an amount within the range of from about 1 to about 10 weight per cent, based on said feedstock.
 12. A process according to claim 11 wherein said olefin is present in an amount within the range of from about 1 to about 5 weight per cent.
 13. A process according to claim 11 wherein: said feedstock comprises 2-methylbutane; said olefin comprises propene; one of said products from said first reaction zone comprises isobutane; and another of said products from said first reaction zone comprises an isohexane.
 14. A process according to claim 1 wherein: said alkylation is carried out in the presence of concentrated hydrofluoric acid; used hydrofluoric acid from said alkylation zone and used hydrofluoric acid from said first reaction zone are passed to a common hydrofluoric acid rerun zone; and rerun hydrofluoric acid from said acid rerun zone is returned as needed to said alkylation zone and to said first reaction zone.
 15. A process according to claim 1 wherein: said olefin is selected from the group consisting of propene, butenes, and mixtures thereof; said feedstock comprises 2-methylbutane; said isoparaffin product containing fewer carbon atoms per molecule than said feedstock comprises isobutane; said isoparaffin product containing more carbon atoms per molecule than said feedstock comprises an isohexane; and said another isoparaffin product containing the same number of carbon atoms as said feedstock comprises 2-methylbutane. 